Solder pellet caster device



March 30, 1943. HUMPHREY 2,315,426

SOLDER PELLET CASTER DEVICE Original Filed Dec; 31, 1940 3 Sheets-Sheet l SOLDER CUHRENT cnsrm Rl-IEO. 260 I52 Ill W; 3 I58 15/ FIG. 2

" THERMOQ 747' 501. DER TIMER INVENTOR R. G. HUMPHREY ATTORNEY March 30, 1943. R. G. HUMP HREY 2,315,426

v SOLDER PELLET CASTER DEVICE Original Filed Dec. 31, 1940 3 Sheets-Sheet 2 FIG. 3 4a 48 g ,4: $53 I42 L a I44 m a n, I g

s i g I 1111111111111. \|n 111111,!11111114 m wqaqal w m 1.22 I20 47 I23 ENTOR R. a HUMPHREY" A T TORNEV March 30, 1943. R. G. HUMPHREY 2,315,426

SOLDER PELLET CASTER DEVICE Original Filed Dec. 51, 1940 3 Sheets-Sheet 5 R. GHU PH EV ATTORNEY Patented Mar. 30, 1943 SOLDEB. PELLET CAST'ER DEVICE Robert G. Humphrey, Pelham, N. Y., assignor to Bell Telephone Laboratories,

Incorporated,

New York, N. Y., a corporation. of New York Original application December 31, 1940, Serial Divided and this application March 13, 1942, Serial No. 434,573

4 Claims.

This invention relates to solder-connecting apparatus and although not limited to such use it is adapted for use in solder-connecting wires to metal surfaces on piezoelectric crystals.

The object of the invention is to provide improved means for solder-connecting wires to metal surfaces.

When the invention is used in connecting a wire to a crystal element the solder connection made is of such form and character that the wire may be used not only as a lead-in wire for the crystal element but also as supporting means for the crystal. 4

In accordance with this invention, a pellet of solder of predetermined size and form is cast on an end of the wire. The pellet is then placed in contact with a suitably prepared metal surface on a crystal element and a solder connection is then made to electrically connect the wire to the metal surface. I

The improvement constituting this invention resides in a caster device for casting on the end of the wire a solder pellet of required size and form.

The caster device may be used in conjunction with the chuck device covered in my copending application R. G. Humphrey Serial No. 372,528, filed December 31, 1940, now Patent 2,283,158, dated May 12, 1942 and of which this application is a division. The chuck device is adapted to hold a wire in position in the caster device of this: invention while a pellet of solder is being cast on. the end of the wire. The chuck device is also adapted to hold the wire with the solder pellet cast thereon Fig.4 is a view in section of parts shown in Fig. 3 and taken on the line l-4;

Fig. 5 is a front view in section of Fig. 3 and taken on theline 5-5;

Fig.6 is a view corresponding in general to Fig. 3 but with certain of the parts operated to different positions;

Fig. 7 is a front view in section of Fi 6 and taken on the line 1--|;

Fig. 8 is a greatly enlarged view of a portion of Fig. 3 and shows a crucible employed in the device shown in that figure;

Fig. 9 is a front View in section of Fig. 8 and taken on the line 9-9;

Fig. 10 is a side view, partly in section, of par shown in Fig. 9 taken on the line |0Hl and showing also a wire and a solder pellet cast in the crucible and a pressure button inserted in the crucible; and s Fig. 11 is an enlarged view of a portion ofthe Wire and the solder pellet cast on the wire.

When the caster device of this invention is used in solder-connecting a wire to a piezoelectric crystal, the caster device is supported on a support on which are also supported the chuck device to hold the wire and the hot plate device to hold and heat the crystal. The arrangement of the devices used in making the solder connection is shown in Fig. 1 in which the devices are supported on a support 3|, the support 3| comprising a U-shaped top 32 with downwardly extend- 'in walls 33 and 34. On the top 32 are mounted manually operated switches 35, 36, 3'! and 38, an ammeter 39, and plug receptacles 40 and 4| to receive electrical supply lines 42 and 43. Manually operated control knobs 44 and 45 are mounted on shafts not shown but which extend through the respective wall members 33 and 34. Set Within the space defined by the inner portion of the top 32 and resting on ledges 46 formed thereon is a slab 41 of suitable insulating material on which are mounted the caster device 48, the chuck device 49, the hot plate device 50 and a reel support 5|. The various devices by means of which the wire connections are made are so arranged and mounted on the support 3| and the slab 41 that the wire connections can be made in a rap-id and accurate manner. The reel support 5! comprises a post 52, secured at its lower end in a flange 53 suitably mounted on the slab 41 by means of screws 54. The upper portion of the post; 52 is bent to provide an axle 55 on which is rotatably supported the reel 56 containing a supply of wire 51. The reel 56 is retained against accidental dislodgement from the axle 55 by means of a cross pin 58. The wir 51 is led downward from the reel 56 to the chuck device 49.

The caster device 48 is used to cast a pellet of solder on the end of the wire 51 and as shown in Figs. 3 tom, inclusive, comprises a crucible H4, a reservoir I I5 for holding a supply of solder paste I I6 and a plunger I IT for forcing the solder paste I I6 into the crucible I I4. The reservoir I I comprises a block I I8 of metal or other suitable material longitudinally bored at II9 to receive the plunger III which projects into one end of the bore II9. The other end of the bore I I9 is closed by means of a relatively long plug I which is held in place by means of a screw I2I extending through an apertured end plate I22. The inner end of the plug I20 is shaped at I23 to provide a dished inclined surface. The top of the block I I8 is longitudinally slotted and milled out to provide a dovetailed track I24 as shown in Fig. 4, to slidably receive a slide bar I 25 having a conical aperture I26 formed therein which may be brought into register with an aperture I2'I in the base of the dovetailed track I24, the aperture I2'I having communication with the reservoir H5. The block H8 is mounted by means of screws I28 on an apertured base plate I29 resting on the slab 41 and secured thereto by means of the screws I30 and a screw holding plate I3I. The slide bar I25 is frictionally engaged at one end by the enlarged head portion I32 of a stud I33, the male-threaded lower end of which is mounted on a manually operated lever I34. Th lever I34 is pivotally supported at one end by means of a screw I35 which extends upwardly into an overhanging flange I36 integral with the end plate I22. The flange I36 is provided. with an elongated curved aperture I3! designed to accommodate movement of the head portion I32 of the stud I33. The slide bar I25 may be longitudinally moved by operation of the lever I34 and relative to the crucible II4 which is supported in a fixed position as will be subsequently explained. A disc I38 of quartz or other suitable material is mounted in the upper surface of the slide bar I25, the slide bar being suitably recessed to receive the disc and the upper surface of the disc being flush with the upper surface of the slide bar. The disc I38 is of larger diameter than the crucible H4 and serves as a removable closure for the bottom of the crucible II4. A small block I39 is mounted by means of a screw I40 on the upper surface of the slide bar I25 and is undercut to provide an overhanging portion I4I which serves as a removable top closure for the top of the crucible II4. A helical spring I42 is provided to bring the slide bar I25 back to normal position, the spring I42 being attached at one end to a pin I43 supported on the slide bar I25 and being secured at the other end to a pin I44 mounted on a tab port-ion I45 of a bridge plate I46, the bridge plate I46 being disposed across the slide bar I25 and secured by means of screws I41 to the top of the block H8.

The crucible I I4 is electrically heated and comprises a ring I48 made of material suitable for transmitting heat to the solder paste in the crucible and for holding the solder when the solder is in a molten condition. I have found that stainless steel may well be used as the material for the ring I48. The ring I48 ha an internal diameter about equal to the diameter of the solder pellet it is desired to cast and is frictionally held in the closed end portion I49 of a U-shaped bar I50 of electrical resistance material. A suitable material for the bar I 50 is a nickel-chromium composition known to the trade as Nichrome. The

.two leg portions I5I-I52 of the bar I50 are connected to suitable source of current supply to heat the bar I50 to a sufiicient temperature to melt solder paste in the crucible I I4, the heat being transmitted through the ring I48 to the solder paste. The ring I43 may be made of electrical insulating material to prevent the electrical current 75 from passing through the ring to the solder paste held therein. It may be made, however, as above mentioned, of stainless steel since the outside of the ring when made of this material soon becomes sufficiently oxidized to prevent the electrical current from passing through the ring. A strip I53 of insulating material is interposed between the leg portions I 5| and I52 of the bar I50 to prevent short circuiting of the leg portions, the strip I53 being held in place by means of suitably insulated screws or bolts, not shown, but which extend through aligned apertures I54 provided in the leg portions I5I, I52, and the strip I53. The bar I50, as shown in Figs. 9, 10 and 4, is supported in an insulating block I55 and rests on an insulating strip I56 the block I55 and the strip I56 being mounted on the upper surface of the block II8 by means of screws I5'I. Spaced electrodes I58 and I 59 are supported in the insulating block I55 and in electrical contact with the leg portions I5I and I52, respectively, of the bar I50 to carry current to the bar I50, the electrodes I58 and I59 extending outwardly of the block I55 a sufiicient distance to permit connection to a suitable source of current supply. An insulating strip I60 is mounted on the block II8 across the insulating strip I56. The strip I60 may be cemented or otherwise secured to the block H8 and serves as an insulating rest for the contact finger I4 on the chuck device 49 when the chuck device is being used over the caster device 48.

The plunger II! is equipped with a manually operated lever I6I which is pivotally supported at one end on a pin I62 which extends through the lever I6I and through one end of a link I63, the other end of the link I63 being pivotally supported on a pin I64 mounted on the undersurface of the overhanging flange I36 of the end plate I 22, the end plate I22 being secured to the block I I0 by means of screws I65 and being apertured at I66 to accommodate an end portion of the link I63. The lever I6I extends through a recess I61 in the outer end of the plunger I I I and is pivotally supported therein by means of a rivet I68.

The caster device 48 in cooperation with the chuck device 49 is used in casting a pellet of solder of predetermined size and form on the end of the wire 51. Fig. 11 shows the pellet I69 cast on the end of the wire 51. The size and form of the pellet I69 are controlled by the internal dimensions of the crucible I I4, the amount of solder paste projected therein and the extent to which the reduced end portion II3 of the button II 2 is inserted in the crucible II4, the button II2 being supported on the chuck device 49 as shown in Figs. 9 and 10 in my original application Serial No. 372,528 above mentioned.

In order to fill the crucible I I4 with the solder paste II6 the slide bar I 25 is moved by means of lever I34 from the position shown in Figs. 3 and 5 to the position shown in Fig. 7, the head portion I32 of the stud I33 serving to transmit movement of the lever I34 to the slide bar I25. In this operation the spring I42 is elongated to provide suflicient spring tension to restore the slide bar I25 to its former position when the lever I34 is released. In the position shown in Fig. 7 the disc I 38 has been removed from the bottom of the crucible I I4 and the conical aperture I26 in the slide bar I25 is in register with the aperture I21 in the block H8 and is in register with the crucible H4. The overhanging portion I4I of the block I39 is over the crucible II4 to close the top of the crucible. While the slide bar I25 is in this position the lever I6I is operated to move the plunger H1 from the position shown in Fig.5 to the position shown in Fig. '7. In this movement solder paste H6 is forced from the reservoir H upwardly through the aperture I21 and the conical aperture I26 and into the crucible II 4, emergence of the solder paste from the top of the crucible H4 being prevented by the overhanging portion I4I of the block I39. The levers I34 and IBI are then in the position shown in Fig. 6. Since the stud I33 has reached an end of the slot I31 further movement of the lever I34 in this direction is prevented.

When the lever I34 is manually released the spring I42 returns the slide bar I and the lever I34 back to the normal position shown in Figs. 3 and 5. In this position the block I39 is away from the crucible H4 so that the overhanging portion MI is no longer over the top of the crucible. The disc I38 is directly under the crucible I I4 and serves as a bottom for the crucible which is filled with the required amount of solder paste H6 for making the pellet I69. A screw I19 equipped with a lock nut I1I is adjustably supported in the outer end of the overhanging portion I36 of the end plate I22 and may be turned to project into one end of the slot I31 to limit the return movement of the lever I34 and the slide bar I25 and so that the disc I38 will be directly under the crucible I I4.

The hot plate device 50 is used to heat a crystal element to a required temperature and to hold the crystal in a required position while a wire is being solderconnected to a metallized surface on the crystal element, the crystal being heated to a temperature slightly below the melting point of the solder to reduce reaction of the crystal when a melting temperature is applied to the point at which the solder connection is being made. I 7

As shown in Fig. l the hot plate device 50 is mounted on the slab 41 in such position that the chuck device 49 may be rotated thereover. In this figure a crystal element I12 is supported on the hot plate device 59 in a position to have for instance, coatings of silver or other suitable material applied to the crystal, for example, by sputtering or by an evaporation process. The stripe I13 is shown as being locatedata nodal point of the crystal but may be located atany other desired point, the point of location being determined by the particular character and form of the crystal and the use required.

As shown in Fig. 2 a caster timer 245 is provided to control with time the application of heating current to the caster device 48. A. solder timer 246 is provided to control with time the application of heating current to the point at which the wire is being sloder-connected to the strip I13 on the crystal I12. These timer devices may be of any conventional character and form suitable for controlling with time the application of the heating current. The thermostat I91 controls the application of heating current to the heating elements I95 located in the hot plate device 50. Suitable rheostats 241 and 248 are provided to control the strength of the currents applied to the respective caster device 48 and the point at which the solder connection is being made on the crystal, the rheostats being labeled Caster Rheo and Solder Rheo. The switches 35 and 36 are provided for respective manual and automatic control of the duration of the current applied to the caster device. The switches 31 and38 provide for respective manual and automatic control of the duration of the current applied to the point of solder connection on the crystal.

Method of making solder connection The crystal I12 with the solder stripe I13 thereon is placed on the hot plate device 50 which is heated by means of the heating elements II95 supplied with current from a suitable source 249 over an obvious circuit. The heating current from the source 249 is automatically controlled by means of the thermostat I91 and a relay 250 which will be energized to open its contact 25I and thus open the current supplying circuit when the contacts of the thermostat I91 close at a predetermined temperature.

The wire 51 is placed between the jaws of the chuck device 49 and is held therein. The chuck device 49 is lifted and rotated to bring the projecting end of the wire 51 over the hot plate device 58. The chuck device 49 is then lowered to bring the end of the wire 51 over a desired point on the stripe i13 on the crystal I14. A suitable flux is applied to the end of the wire 51 and the fluxed end of the wire is brought into engagement with the stripe I13 so that some of the flux on the wire will be deposited on the stripe I13.

The chuck device 49 with the wire 51 therein is then lifted and rotated over to the caster device 49 and is lowered to bring the end of the wire 51 into the crucible I I4, the end of the wire 51 being thrust into the crucible H4 until the wire 51 touches the disc I38 which at the time serves as a bottom for the crucible. A screw 252 provided with a lock nut 253 is adjustably mounted on the slab 41 as shown in Fig. 4 to limit downward movement of the arm 59 of the chuck device 49 to prevent undue thrusting of the end of the wire 51 into the crucible H4.

The chuck device 49 is operated to hold the wire 51 so that a predetermined length of the wire will project below the button H2, the jaws of the chuck being operated to a closed position by means of the electromagnet 52 which is energized from the source of current supply 1I when the switch 10 is closed. The chuck device 49 is lifted and swung to the position shown in Fig. 1 so that the end of the wire 51 is removed from the crucible H4.

' The caster device 48 is operated to fill the crucible H4 with solder paste in the manner above described. The chuck device 49 is lifted again and swung to a position over the crucible H4 and so that the end of the wire 51 is thrust into the crucible, the depth of thrust being limited by the screw 252 against the undersurface of the arm 59. heated by current supplied from the source H. For manual control of the duration of the heating current for the caster device 48 the switch 35 is operated. This closes the following circuit: source of current supply 1I, conductor 254, conductor 255, ammeter 39, conductor 256, conductor 251, contact of switch 35, conductor 258, caster rheostat 241, conductor 259, electrode I58, leg

The crucible H4 is electrically ISI, leg I52, electrode i551, conductor 260, conductor 26i, conductor 13 to source of current supply H. The crucible is heated to a suiiiciently high temperature to melt the solder paste in the crucible H4. The reduced end portion H3 of the button H2 is pressed downwardly within the crucible M4 by the weight of the chuck device 39 while the solder paste is being brought to a molten condition. The ring-shaped form of the crucible H4 and the pressure of the button H2 makes the solder take the form of the pellet I59, shown in Fig. 11, when the operating current for the caster device is shut off by opening of the switch 35. It will be seen, therefore, that a pellet H59 of solder of predetermined size and form is cast on the end of the Wire 51. Automatic timing of the duration of the heating current may be obtained by closing the switch 35 instead of the switch 35.

The chuck device 49 is lifted and rotated to bring the wire 51 with the solder pellet I59 cast thereon directly over the stripe E3 on the crystal H2 and the chuck device 49 is then lowered to bring the pellet 189 into engagement with the stripe I13. In this position the contact finger M on the chuck device 49 touches the metal coating IN or the stripe I13 on the crystal to close an electrosoldering circuit as follows: source of current supply it, conductor 254, conductor 255, ammeter 39, conductor 2 .32, solder rheostat 248, conductor 283, contacts of switch 3?, conductor 264, conductor L conductor ll, arm 5-9 and jaws 60 and Si, wire 51, solder pellet E59, strip H3, finger contact M, conductor 265, to source of current supply 1 l. Since the hot plate device 50 is maintained at a temperature only slightly below the melting point of the solder in the pellet I69 the current applied to the point of engagement of the solder pellet I59 and stripe H3 is sufficient to raise the temperature at this point of contact to a melting temperature from the solder. The material in the solder pellet I69 and in the stripe IE3 is therefore sufiiciently heated to make the parts fuse together. The current applied may be regulated by operation of rheostat 248. If it is desired to automatically regulate the duration of the current supplied this may be accomplished by closing the switch 38 instead of the switch 31, the solder timer 245 then functioning to control the duration of the current supply.

After the wire 5'! is solder-connected to the stripe I13 on the crystal I12 the wire 51 is severed at a required point to leave a relatively small length of the wire extending from the crystal.

This small length of wire may be used as a leadin wire for the crystal and also as the supporting wire for the crystal.

An explanation in detail of the structures of the chuck device 49 and the hot plate device 50 is given in my original application Serial No. 3'7 2,528 filed December 31, 1940 and to which reference may be had for an explanation of parts shown and numbered in the drawings in the present application and not described in that application.

What is claimed is:

1. A solder pellet caster device comprising a reservoir adapted to hold a supply of solder in paste form, a crucible open at its top and bottom and. supported above said reservoir, means to heat said crucible, an apertured slide bar operating between said reservoir and said crucible and carrying in spaced relation a closure for the top and a closure for the bottom of said crucible, the aperture in said slide bar being in register with said crucible and said reservoir when the top of said crucible is closed, means to operate said slide bar, and. means operating in said reservoir to force the solder paste in said reservoir into said crucible when the bottom of said crucible is open.

2. A solder pellet caster device comprising in combination an apertured block adapted to hold a supply of solder in paste-like form, a plunger supported in said block and operable to move said paste, a crucible supported on said block, said crucible being open at its top and bottom, means for heating said crucible, an apertured slide bar supported in said block and carrying spaced closures for the top and bottom of said crucible, said slide bar being operable to move said closures relative to said crucible, and said plunger being operable to force said paste through the aperture in said slide bar and into said crucible when the top and bottom of said crucible are respectively closed and open.

3. A solder pellet caster device comprising a body member formed to provide a reservoir for a supply of solder in paste form, an apertured slideway formed in said body member, th aperture in said slideway being in communication with said reservoir, a slide bar operating in said slideway and having an aperture formed therein, a crucible open at its top and bottom and supported above and in frictional engagement with said slide bar, means to heat said crucible, a top closure and a bottom closure for said crucible carried by said slide bar, and arranged in spaced relation on said slide bar, said top closure extending in spaced relation over the aperture in said slide bar, means to operate said slide bar to selectively bring said top and said bottom closures in register with said crucible, plunger means extending into said body member and operable to force the solder paste in said reservoir into said crucible when said crucible is open at the bottom and closed at the top, and means to operate said plunger means.

4. A solder pellet caster device comprising an apertured block constructed to form a reservoir for a supply of solder paste, a plunger extending into said block and operable in the reservoir formed therein to apply pressure to the solder paste in the reservoir, means to operate said plunger, an apertured slideway formed into said block, an apertured slide bar supported in said slideway, means to operate said slide bar, a crucible open at its top and bottom and supported above said slide bar, means supporting said crucible, heating means for said crucible, a top closure for said crucible supported on said slide bar, a bottom closure for said crucible supported on said slide bar and in spaced relation with said top closure, said slide bar being operable to bring the aperture in said slide bar into register with the open bottom of said crucible, and said top closure across the top of said crucible, said plunger being operable to force solder paste from the reservoir in said block and through the aperture in said slide bar and into said crucible and said slide bar being also operable to move said top closure away from said crucible and the bottom closure into registry with said crucible.

ROBERT G. HUMPHREY. 

